Four Tips to Optimize Email Marketing through Variable Testing

email marketing Jul 29, 2021
email variable testing

Are you getting the best possible results from your email marketing? Email testing of multiple variables such as timing, subject line and email “from” name are a great way to find the mix that reaches your audience most effectively. It is even more important now than ever that your email is reaching your audience in the most effective way. In fact, only 21% of promotional emails are opened. Testing different email variables can boost your open and click rate, taking your email marketing to the next level.

However, it is important to keep best practices in mind when variable testing to ensure the results are valid and accurate. Inconsistencies in testing methods can cause more issues than not and could harm your email marketing performance. Here are our recommendations to make sure you get accurate data to optimize your email campaigns:

Test One Variable at a Time

When it comes to email testing, it is important to test one variable at a time so that you can get an accurate understanding of how the variable affected your email performance. For example, for your next few newsletter sends you can test the “from” name of your email, and gain insight into which your audience responds best by analyzing the open rates. Once you have identified the top-performing “from” name, you can apply it to future emails and in the next set of emails test a new variable-- for example, the subject line. By limiting each test to one variable, you will be able to accurately assess the results and fully understand how simple changes can affect your email performance.

Choose the Best Test Group Size

In order for your tests to be accurate, you must have a large enough sample size. For email testing, a sample size of 500 is low, but a good place to start. The larger your sample size, the more likely your results will be statistically accurate. If you don’t have enough members in your database, your results may be inaccurate and send your email marketing strategies in the wrong direction. However, sample size also depends on the number of subscribers you send emails to normally. Campaign Monitor provides a formula to help you decide what the right sample size would be for your variable testing.

This sample size calendar from Evan Miller is interactive and can help you know your test group size. Here is a quick breakdown of what’s included and what each value means in the formula:

  • Baseline Conversion Rate: This is the average open percentage of your emails.
  • Minimum Detectable Effect (MDE): This is your smallest difference that you want to detect from your campaign test. By setting the MDE to a certain percentage, it gives you the range of what is not distinguishable from the baseline. Anything outside this range would be a noticeable change and should be flagged.
  • Statistical Power: The probability of a false negative. So, if you set it at 90%, there is a 10% chance you would not see the impact.
  • Significance Level: This shows the chance of a false positive. So, if you set it at 10%, there is a 10% chance that you would see an impact even though in reality, there wasn’t an impact.

Randomly Select Members of Your Test Groups

When splitting up your recipient list for email testing, do so randomly. Splitting the recipient list randomly prevents testing bias and will help your results be a more accurate sample of the population as a whole. If using an email marketing platform, it is likely it will have a random list generator function. If, on the other hand, you need to manually select members, make sure you sort them in a way that is truly random. For example, it is not recommended that you sort by company name or titles, as you are likely to have too many contacts from similar places in each list. However, if you sort by email address or last name, you are more to generate a random sample.

Track and Analyze Results

It is important to monitor what variables you have tested and how they have changed your email marketing results. Without keeping track of the results, the information you have gathered isn’t useful.  To do this, keep a log of the variables you have tested for each campaign, the results you saw and any observations you have made along the way. Doing this will help you keep track of what you have tested and provide great insight into what you should test to continuously improve results.

Regular email testing is critical, as the industry changes frequently. Email marketing trends may impact your promotional email practices—everything from real personalization to the Covid-19 pandemic. By following the steps above, you will ensure that your email campaigns are getting the greatest ROI for your marketing team.

Looking for more best practices and actionable tips to elevate your marketing? Check out Marketing Pro Series online and on-demand marketing courses. Accompanied with 1:1 coaching by senior-level expert marketers, self-paced courses and interactive templates, our courses are designed to help your business use marketing as a tool to boost revenue and lead generation.

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